Sorting particles

ABSTRACT

A device for sorting particles. The device may include a channel structure that defines a channel having an inlet and first and second outlets. The device also may include first and second transport mechanisms. The first transport mechanism may be configured to create a particle stream of first particles and one or more second particles. Each particle may move along the channel from the inlet toward the first outlet and may be disposed in a fluid supported by the channel structure. The second transport mechanism may be configured to be pulse-activated to selectively move at least one of the second particles from the particle stream and toward the second outlet.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. patent application Ser. No.10/763,112, filed on Jan. 21, 2004, now U.S. Pat. No. 7,389,879 which ishereby incorporated by reference.

BACKGROUND

Cells and other particles are often obtained as mixtures of two or moredifferent types. For example, blood or tissue samples from patients mayinclude a mixture of many different cell types that mask the presence orproperties of a particular type of cell that is of interest.Accordingly, the cells of such samples may need to be sorted with a cellsorting device, such as a fluorescence-activated cell sorter, toidentify, purify, and/or characterize cells of interest in the samples.However, cell sorters can be expensive and complex to operate andmaintain.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a system for sorting particles, inaccordance with an embodiment of the invention.

FIG. 2 is a schematic view of a sorter unit that may be included in thesystem of FIG. 1, in accordance with an embodiment of the invention.

FIG. 3 is a schematic view of another system for sorting particles andparticularly cells, in accordance with an embodiment of the invention.

FIG. 4 is a partially schematic view of the system of FIG. 3, inaccordance with an embodiment of the invention.

FIG. 5 is a bottom view of selected portions of a substrate assemblyincluded in the system of FIG. 4, in accordance with an embodiment ofthe invention.

FIG. 6 is a fragmentary bottom view of a sorter unit included in thesubstrate assembly of FIG. 5, as the sorter unit sorts cells, inaccordance with an embodiment of the invention.

FIG. 7 is a fragmentary sectional view of the sorter unit of FIG. 6,taken generally along line 7-7 of FIG. 6, in accordance with anembodiment of the invention.

FIG. 8 is a bottom view of a manifold disposed above the substrateassembly of FIG. 5 in the system of FIG. 4, in accordance with anembodiment of the invention.

FIG. 9 is a bottom view of an upper layer of the manifold of FIG. 8, inaccordance with an embodiment of the invention.

FIG. 10 is a sectional view of the manifold of FIG. 8, in accordancewith an embodiment of the invention.

DETAILED DESCRIPTION

A system, including method and apparatus, is provided for sortingparticles, such as cells. The system may include two transportmechanisms for moving particles. A first of the transport mechanisms maybe a nonselective mechanism configured to move a set of particlesrelatively continuously and nonselectively. The nonselective mechanismmay operate, for example, by exerting a pressure on a fluid in which theset of particles is disposed and/or may exert a force on the set ofparticles in relation to the fluid, such as by dielectrophoresis. Asecond of the transport mechanisms may be a selective mechanismconfigured to selectively move a subset of the particles relative toother particles of the set, as the nonselective mechanism operates.Accordingly, the second transport mechanism may be pulse-activated atsuitable times to selectively apply a force on particles of the subset.The force may be a pressure pulse exerted on a fluid segment in whichthe subset of particles is disposed. The force may be directedtransversely to the direction in which the set of particles istransported by the nonselective transport mechanism, to move the subsetof particles along a different path, thereby sorting the set ofparticles. Methods of sorting particles using a combination of selectiveand nonselective transport mechanisms are also disclosed.

FIG. 1 shows a system 20 for sorting particles using a plurality of “n”sorters 22 configured to operate in parallel. The system may include anysuitable number of sorters including only one. The sorters may bedisposed in parallel fluid communication with an input reservoir 24holding an input mixture 26 of two or more types of particles, such asparticles A and B, in a fluid. Fluid communication between the inputreservoir and the sorters may be provided by a conduit network 28.Portions of the input mixture may be directed to the various sortersfrom the conduit network as separate streams of particles. Each sortermay selectively move the A and B particles of a stream along differentpaths 30, 32, so that the mixture is enriched for A or B particles,respectively, in different intermediate sites 34. Sorted particles ofeach type from each sorter may be combined, shown at 36, so that Aparticles and B particles are directed to their respective receiverstructures 38, 40.

A sorter may be any device or mechanism for enriching a particle mixturefor at least one type of particle in the particle mixture relative toother types of particles in the mixture. The sorter may be configured tomove one or more types of particle from a default path of particle/fluidmovement to an alternate path (or a plurality of alternate paths).Alternatively, the sorter may move different types of particles from adefault path of movement to different alternate paths according to thetype of particle.

The sorter may apply a force on a fluid volume or fluid segment in whicha particle is disposed or may apply a force on the particle selectivelyin relation to the fluid volume. The force may be a pressure exerted onthe fluid volume, a dielectrophoretic force on the particle, anelectroosmotic force on the fluid, etc. In some embodiments, the sortermay sort by changing the path followed by fluid and particles, forexample, for opening and/or closing valves, among others.

Sorters may be configured to operate concurrently, for parallel sortingfrom an input mixture. Alternatively, or in addition, sorters may bedisposed in series for sequential sorting, for example, to provideprogressive enrichment of a mixture for a particular type of particle.Enrichment, as used herein, may include any increase in therepresentation of one particle type relative to one or more otherparticle types of a mixture. For example, enrichment may increase therepresentation of a particular type of particle from a lower to a higherpercentage of the particle total, and/or may substantially or completelyseparate the particular type of particle from one or more other types ofparticles.

An input reservoir may be any vessel (or vessels) configured to receivethe input mixture and release portions of the input mixture to asorter(s). Release of the portions may be passive, such as throughpassage that is always in fluid communication with the input reservoir,or active, such as with valve that operates to release portionsselectively. The input reservoir may be a well, a chamber, a channel, asyringe, etc.

A conduit network may be any set of passages that provide fluidcommunication between the input reservoir and the sorters. The conduitnetwork may include tubing, channels formed in or on a generally planaror three-dimensional channel structure, and/or a combination thereof,among others. The conduit network may include a set of parallel passagesthat extend from the input reservoir to the sorters, passages thatincrease in number or branch toward the sorters, or a combinationthereof. For example, in the present illustration, conduit network 28carries portions of mixture 24 in parallel through a single conduit 42that branches to a plurality of conduits 44 equal in number to thenumber of sorters. The conduit network may be defined by a manifold, asdescribed below.

An output receiver structure may be any vessel or compartment forreceiving fluid and sorted particles from the sorters. Exemplaryreceiver structures may include microplate wells, microfluidiccompartments of a chip, test tubes, culture vessels, etc. In someembodiments, each sorter may direct sorted particles to a separatereceiver structure, for example, to perform post-sorting processing. Thepost-sorting processing may include cell culture, cell lysis, and/ormolecular analysis (sensing) of cellular or particle constituents (suchas analysis of a nucleic acid, protein, lipid, ion, carbohydrate, etc.).In an exemplary embodiment, post-sorting processing may include celllysis followed by amplification of a nucleic acid.

An input mixture may include any particle mixture of interest.Particles, as used herein, may include any set of discrete, smallobjects. For example, the particles may be less than about 100micrometers in diameter, and may be biological, synthetic, naturallyoccurring, organic, inorganic, or a combination thereof. Exemplaryparticles may include cells. The cells may be alive or dead, fixed orunfixed, processed or unprocessed, cultured or noncultured, and/or thelike. Exemplary cells may include eukaryotic cells and/or bacteria.Other exemplary particles may include viruses, organelles, vesicles,synthetic polymers, beads, coded beads carrying biomolecules, magneticparticles, and/or the like. Exemplary sources for particle mixtures mayinclude a patient sample (such as blood, a tissue biopsy, mucus, saliva,urine, sperm, tears, sweat, etc.), an environmental sample (such as asample from water, air, soil, etc.), and/or a research sample, amongothers.

The input mixture may be preprocessed before sorting. For example, theinput mixture may be treated to make a subset of the particles opticallydistinguishable. In some embodiments, the mixture may be treated with adye to selectively label a subset of the particles. The dye may be anyoptically detectable material. The dye may bind directly to theparticles or bind through a coupled (covalently or noncovalently)specific binding member, such as an antibody, a lectin, a molecularimprinted polymer, a nucleic acid, a receptor, a ligand, etc.Alternatively, or in addition, the input mixture may be cells that havebeen engineered, such as by transfection, to express an opticallydetectable material, such as green fluorescent protein.

FIG. 2 shows an example of a sorter unit 50 that may be included insystem 20. Sorter unit 50 may include a channel structure 52 defining atleast one channel 54. Channel structure 52 may be any structure thatdefines a passage along which particles (and fluid 53) may betransported. The passage may be any predefined path for particle/fluidtravel. In addition, the passage may include walls and/or a particleguiding and/or fluid guiding surface characteristic, such as adjacenthydrophobic and hydrophilic surface regions. The channel structure maysupport the particles by supporting fluid in which the particles aredisposed. Supported fluid, as used herein, is fluid that is in contactwith a solid surface so that the fluid is restricted from falling. Bycontrast, unsupported fluid may include airborne fluid droplets. In someembodiments, the channel structure may be a substrate assembly includinga substrate and a fluid barrier connected to the substrate, as describedfurther below.

Channel 54 may include an inlet 56 at which a stream 58 of particles 60,62 may be received, and first and second outlets 64, 66 to which theparticles may travel. Accordingly, channel 54 may be described as abranched channel because particles and/or fluid may travel along two ormore different paths 68, 70 through the channel.

Sorter unit 50 also may include a sensor 72 configured to sense aproperty of each particle 60, 62. The sensor may be an optical sensorthat measures an optical (or electromagnetic) property of each particle,such as a luminescence (photoluminescence (for example, fluorescence orphosphorescence), chemiluminescence, or bioluminescence), scattering,absorbance, refraction, reflection, and/or polarization, among others.Alternatively, the sensor may be an electrical or magnetic sensor,configured to sense an electrical or magnetic property of the particles,respectively.

Sensor 72 may have any suitable size, shape, location, and structure. Insome embodiments, the sensor may be longer than the diameter of theparticles, that is, long enough to sense a particle at a pluralitypositions along the channel, for example, to measure the velocity of theparticle. Accordingly, the sensor may be a single sensor or a pluralityof sensor elements, which may be arrayed, for example, along thechannel. The sensor also may have any suitable width including a widthsubstantially similar to the width of the channel. The sensor may beformed on or below a surface of the channel, for example, one or morephotodiodes formed on or in a substrate that defines a floor of thechannel. The photodiodes may be configured to receive light selectively.Accordingly, they may be coated with a photoselective material, such asa filter layer that selectively permits the passage of particularwavelengths of light.

Sorter unit 50 may include, and/or function with, a plurality ofmechanisms for moving particles and/or fluid, such as nonselective andselective transport mechanisms 74 and 76, respectively.

Nonselective transport mechanism 74 may be any mechanism(s) for movinginput particles relatively nonselectively through channel 54. Thenonselective transport mechanism may exert a similar force on differenttypes of particles in a particle mixture so that they travel with asimilar velocity. Alternatively, the nonselective transport mechanismmay exert dissimilar forces so that different particles travel withdifferent velocities. However, in either case, the nonselectivetransport mechanism moves the particles through the channel. Thenonselective transport mechanism may be a continuous transportmechanism. A continuous transport mechanism, as used herein, may be anytransport mechanism that moves a plurality of particles through thechannel without substantial interruption.

In the present illustration, nonselective transport mechanism 74 sends astream 58 of particles 60, 62 into and through the channel to defaultpath 68 (without operation of selective transport mechanism 76). Astream, as used herein, is a succession of moving particles created byentry into, and movement of the particles along, the channel. Thesuccession may be relatively steady or intermittent and may introduceparticles into the channel one by one, that is, in single file, or twoor more at once in a side-by-side or random arrangement, among others.In some embodiments, the diameter of the channel may be small enough torestrict the particles to movement in single file.

The nonselective transport mechanism may operate by any suitablemechanism. For example, the nonselective transport mechanism may operateby exerting a force on a fluid in which the particles are disposed, topromote bulk fluid flow and concomitant bulk particle flow.Alternatively, this transport mechanism may exert a force on theparticles relative to the fluid, to promote bulk particle flow throughthe fluid. The nonselective transport mechanisms may apply a positive ornegative pressure to the fluid, generally upstream (toward the inputmixture) or downstream (toward the receiver structures), respectively,of channel 54, so that there is a pressure drop along the channel.Exemplary nonselective transport mechanisms may include pressurized gas,a positive displacement pump (such as a syringe pump), a vacuum, and/ora peristaltic pump, among others. Other exemplary nonselective transportmechanisms may include electrodes arrayed to providedielectrophoretic-based movement of the particles, for example, usingtraveling wave dielectrophoresis to propel a mixture of particles alongthe channel.

Sorter 50 also may include selective transport mechanism 76 thatcooperates with nonselective transport mechanism 74. The selectivetransport mechanism may be any mechanism(s) configured to selectivelymove a subset of one or more particles of a mixture along a differentpath than other particles of the mixture.

The selective transport mechanism may be configured to act on individualparticles or sets of particles of the mixture. In some embodiments, theparticles of stream 58 may be spaced sufficiently so that singleparticles may be displaced from the stream. Alternatively, the particlesmay not be spaced sufficiently, so that two or more particles may bedisplaced together. In either case, an enrichment of the mixture for aparticular type(s) of particle, particularly a minor particle, mayoccur.

The selective transport mechanism may be pulse-activated, to provide atransient action on selected particles. Pulse-activated, as used herein,means activated by a transient signal pulse or a by a plurality oftransient signal pulses. The transient signal pulses may be produced asneeded to sort particles, generally separated by irregular timeintervals, rather than being a steady signal or periodic signalsoccurring at regular intervals. Exemplary signal(s) may be an electricalsignal (such as a current or voltage pulse) or an optical pulse thatactivates a phototransistor, among others.

The transient action on the selected particles and/or the transientsignal pulses that activate the transport mechanism may be fast, thatis, lasting for less than about one second. In some examples, thetransient action may be a pressure pulse that lasts less than about tenmilliseconds or less than about one millisecond, depending on parameterssuch as fluid viscosity, channel dimensions, channel geometry, etc.

The selective transport mechanism may have any suitable maximumfrequency of transport. The maximum frequency of transport is themaximum frequency of pressure pulses that can be produced per second andtherefore the maximum number of particles that can be displaced by theselective transport mechanism per second. In some examples, the maximumfrequency may be at least about 100 hertz or at least about onekilohertz.

Selective mechanism 76 may be configured to operate concurrently withnonselective mechanism 74, that is, selective transport mechanism 76 maydisplace selected particles 62 from a particle stream created byoperation of the nonselective transport mechanism. In some embodiments,the selective transport mechanism may be configured to exert a pressurepulse locally on a fluid volume in channel 54, for example, on a fluidsegment or fraction 78 disposed adjacent second outlet 66, to directparticles 62 along second path 70.

Exemplary selective transport mechanisms may be formed by thin-filmelectrical devices, such as thin-film heaters (for example, resistivelayers) and piezoelectric elements, among others. Such thin-filmelectrical devices may be actuated rapidly with an actuation pulse toprovide a transient pressure pulse. Thin-films, as used herein, are anyfilms that are formed on a substrate. The thin-films may be formed byany suitable method, such as vapor deposition, sputtering,magnetron-based deposition, and/or plasma-enhanced deposition, amongothers. Individual layers of the thin-films may have any suitablethickness, or a thickness of less than about 500 μm, 100 μm, or 20 μm.Alternatively, or in addition, the individual thin-film layers may havea thickness of greater than about 10 nm, 20 nm, or 50 nm.

Alternative sorter unit 80, also including portions shown here inphantom outline, may include a second channel 81 disposed adjacent firstchannel 54. Second channel 81 may include an inlet 82 and an outlet 84.First and second channels 54, 81 may be in fluid communication, forexample, connected by a passage 86. Second channel 81 may be operatedupon by a fluid transport mechanism 88 configured to send a stream ofanother fluid 90 along a third path 92, which may be substantiallyparallel to first path 68. Accordingly, particles displaced from stream58 into passage 86 may join fluid stream 90 and exit channel 81 throughoutlet 84.

The same reference indicators are used to refer to the same systemcomponents throughout the discussion of FIGS. 3-10 below. Thus, to makeit easier to understand the relationship between different drawings,selected drawings may include reference indicators for system componentsthat are discussed primarily or exclusively in the context of otherdrawings.

FIG. 3 shows a schematic view of a system 110 for sorting cells or otherparticles. System 110, and other sorter systems described by the presentteachings, may provide environmental isolation of biological material,such as isolation of potentially hazardous material from a user of thesystem.

System 110 may include a sorter assembly 112. The sorter assembly may beinterfaced electrically with system control electronics 114 and aprocessor included therein. The sorter assembly also may be interfacedfluidically with a cell input mixture 116 and, optionally, a separatefluid source 118, through a manifold 120 for routing fluid. Furthermore,the sorter assembly may be interfaced optically with a light source 122.Cells and fluid may be moved from cell input mixture 116 and fluidsource 118 by one or more particle/fluid transport mechanisms, such aspressure controllers 124, 126, which may apply a negative pressuredownstream from sorter assembly 112 and manifold 120. The pressurecontrollers and the light source also may be interfaced with the systemcontrol electronics, shown at 128, 130, to provide, for example,processor-based control of fluid/particle transport and light exposure.Accordingly, light source 122 may be a constant source or a pulsedsource, among others.

In operation, cells of input mixture 116 may enter and exit sorterassembly 112 via manifold 120, before and after sorting, respectively.When the cells exit the sorter assembly and manifold, they may representenriched populations, such as target cells 132 and waste cells 134. Invarious embodiments, the target cells may be re-sorted, cultured, and/oranalyzed molecularly or on a cellular level, among others. Waste cells134 may be discarded. Alternatively, the “waste” cells may be anotherpopulation of interest to be processed further.

Sorter assembly 112, also termed a substrate assembly, may include anelectrical portion 136 interfaced with a fluidic portion 138. Electricalportion 136 may include a plurality of thin-film devices 140, such asswitching devices (transistors, diodes, etc.), temperature controldevices (heaters, coolers, temperature sensors, etc.), transducers,sensors, etc. Accordingly, electrical portion 136 may be an electronicportion with flexible circuitry. Fluidic portion 138 may define aplurality of sorter channels 142 that create the fluidic aspects of thesorter units.

FIG. 4 is a partially schematic view of system 110. System 110 mayinclude a sorter device 150 that includes sorter assembly 112 connectedadjacent manifold 120. Sorter device 150 also may include one or moreinput reservoirs 152, 154, output reservoirs 156, 158, and pressurecontrollers 124, 126. The input and output reservoirs may be anysuitable vessels or fluid receiver structures. The sorter device alsomay include system control electronics 114 and light source 122.Alternatively, the system control electronics, light source, pressurecontrollers, and/or one or more reservoirs may be separate from thesorter device. For example, sorter device 150 may be configured as areusable or single-use cartridge that electrically couples through anelectrical interface 160 to a control apparatus 162.

Sorter device 150 may function in system 110 as follows. Cell inputmixture 116 and fluid 118 may be pulled into sorter assembly 112 due tonegative pressure exerted by pressure controllers 124, 126. The cellmixture and fluid may travel from cell and fluid input reservoirs 152,154, through respective conduits 164, 166 and manifold 120 into sorterassembly 112. Without any sorting by the sorter assembly, portions offluid 118 from fluid input reservoir 154 may pass back through themanifold to be received in target reservoir 156 from conduit 168. Inaddition, portions of input mixture 116 may be received in wastereservoir 158 from conduit 170. However, the action of sorter assembly112 displaces target cells 132 from mixture 116 so that they are placedselectively in target reservoir 156.

FIG. 5 shows a bottom view of selected portions of sorter assembly 112of sorting device 150. The sorter assembly may include a substrate 180having a plurality of thin-film electrical devices 140. The sorterassembly also may include a plurality of sorter units 182, delineatedhere generally as a three-by-three array of dashed boxes. The substratemay define a plurality of openings, such as feed holes 184, throughwhich fluid and particles may pass, to and/or from the adjacent manifold120 (see FIG. 4). Feed holes 184 may be arranged in columns, shown at185. Each column 185 may be aligned with a first-layer manifold conduit,such as conduits 186 a-186 d, which are shown in dashed outline anddisposed adjacent an opposing surface of the substrate. Manifoldconduits are described in more detail in relation to FIGS. 7-9. A fluidbarrier that cooperates with the substrate to form channels is disposedadjacent the substrate but is shown elsewhere (see FIGS. 6 and 7).

Substrate 180 may have any suitable structure and composition. In someembodiments, the substrate may be generally planar. The substrate may beformed of a semiconductor, such as silicon or gallium arsenide, amongothers, or of an insulator, such as glass or ceramic. Accordingly,thin-film devices may be fabricated in and/or on a semiconductor, or onan insulator, for example, by flat panel technology. The substrate mayprovide feed holes 184, so that the manifold is disposed adjacent asubstrate surface that opposes the thin-film devices. Alternatively,feed holes 184 may be defined above the substrate adjacent the samesubstrate surface as the thin-film devices. Accordingly, a fluid barrierdisposed connected to the substrate adjacent the thin-film devices mayinterface with the manifold (see below).

The sorter assembly may include any suitable number of sorter units inany suitable arrangement. For example, the sorter assembly may includemore than ten or more than one-hundred sorter units. In someembodiments, the sorter units may be arranged in a two-dimensionalarray, which may be rectilinear, among others.

FIG. 6 shows a sorter unit 182 included in sorter assembly 112, as thesorter unit sorts cells 132, 134. A fluid barrier 196, shown here infragmentary sectional view, may be connected to substrate 180 to definethe walls of adjacent channels 198, 200 that receive fluid and/or cells.In particular, channel 198 may receive fluid carrying cells 132, 134from first manifold conduit 186 a and through feed hole 184 a. The cellsmay travel along the channel to exit at feed hole 184 b, whichcommunicates with fourth manifold conduit 186 d. Channel 200 may receivea fluid from second manifold conduit 186 b and feed hole 184 c, shown at204. The fluid may travel along channel 200 to exit at hole 184 d, whichcommunicates with third manifold conduit 186 c.

Sorter unit 182 may include a sensor 210 and a transport mechanism 212that is selectively actuated based on information from the sensor.Sensor 210 may be disposed upstream of a passage 214 that connectschannels 198, 200. The sensor may sense a property of each cell thatpasses over the sensor. If the property meets a predefined criterion,transport mechanism 212 may be actuated at a suitable time after sensingthe cell, for example, based on a predicted arrival time of the celladjacent passage 214.

Transport mechanism 212 may include a thin-film electrical device 216that displaces selected cells from channel 198 when pulse-activated.Electrical device 216 may be a thin-film heater or a piezoelectricelement, among others. Thin-film device may exert a force transverse tochannel 198, that is, transverse to a default path 220 along which thecells travel. The force may be directed selectively toward passage 214,from an opposing passage 222, by the use of fluid diodes 224. The fluiddiodes may be any conduit structure that selectively restricts flow inone direction, for example, upward from channel 198 in the presentillustration. Other exemplary fluid diodes that may be suitable areincluded in U.S. Pat. No. 4,216,477 to Matsuda et al., which isincorporated herein by reference.

Fluid moved by a pressure pulse from transport mechanism 212 may besupplied by feed hole 184 e, which communicates with second manifoldconduit 186 b, or from a separate fluid source. The pressure pulse maydisplace cell 132 from upper channel 198 to lower channel 200. The cellthen may join fluid flowing in channel 200 to exit at feed hole 184 d.

FIG. 7 shows a sectional view of the sorter unit 182 and adjacentregions of sorter device 150. Substrate assembly 112 may adjoin manifold120, particularly a first manifold layer 240 that defines first manifoldconduit 186 a. A second manifold layer 242 may be spaced from thesubstrate assembly.

Substrate assembly 112 may include substrate 180, thin-film layers 244formed adjacent the substrate's surface (in or on the substrate), andfluid barrier 196 connected to the substrate and thin-film layers. Thethin-film layers may define electrical portion 136 of the substrateassembly, particularly thin-film electrical devices 140 thereof. Fluidbarrier 196 may be formed unitarily or, as shown in the presentillustration, may be formed of a channel layer 246, and a cover layer248. The channel layer may define walls 250 of channel 198. Channellayer 246 may be formed from any suitable material, including, but notlimited to, a negative or positive photoresist (such as SU-8 or PLP), apolyimide, a dry film (such as DUPONT Riston®), and/or a glass. Methodsfor patterning the channel layer 246 may include photolithography,micromachining, molding, stamping, laser etching, and/or the like. Coverlayer 248 also may define a wall of channel 198. The cover layer may beformed of an optically transparent material, such as glass or plastic,to permit light from the light source to enter channel 198.

FIG. 8 shows a bottom view of first manifold layer 240 of manifold 120.Manifold layer 240 may include a plurality of openings 260 extendingthrough the manifold layer and aligned with manifold conduits, such asfirst-layer manifold conduits 186 a-d defined by grooves 262 of thefirst manifold layer in abutment with substrate 180 (see FIG. 5).Accordingly, openings 260 are disposed in fluid communication withcolumns 185 of feed holes 184 (see FIG. 5) via the first-layer manifoldconduits.

FIG. 9 shows a bottom view of a second layer 242 of manifold 120. Secondlayer 242 may include second-layer openings 270 extending through thesecond layer from grooves 272 formed in the second layer. Each groove272 may be configured to be aligned with a row of first-layer openings260 from first manifold layer 240 (see FIG. 8). First-layer openings 260are shown in phantom outline in this view to simplify the presentation.Each groove 272 may form a second-layer conduit 274 by abutment of thefirst and second manifold layers. Each second-layer conduit 274 mayprovide fluid communication between a row of first-layer openings 260and thus a plurality of corresponding columns of feed holes 184 in thesubstrate (see FIG. 5).

FIG. 10 shows a sectional view of manifold 120 of sorter device 150.Fluid may travel from columns of substrate feed holes (see FIG. 5),through first-layer conduits 186, and then through a second layerconduit 274 to tubing 170.

The devices and methods described herein may be microfluidic devices andmethods. Microfluidic devices and methods receive, manipulate, and/oranalyze samples in very small volumes of fluid (liquid and/or gas). Thesmall volumes are carried by one or more passages, at least one of whichmay have a cross-sectional dimension or depth of between about 0.1 to500 μm, or less than about 100 μm or 50 μm. Accordingly, fluid at one ormore regions within microfluidic devices may exhibit laminar flow withminimal turbulence, generally characterized by a low Reynolds number.Microfluidic devices may have any suitable total fluid capacity.

It is believed that the disclosure set forth above encompasses multipledistinct embodiments of the invention. While each of these embodimentshas been disclosed in specific form, the specific embodiments thereof asdisclosed and illustrated herein are not to be considered in a limitingsense as numerous variations are possible. The subject matter of thisdisclosure thus includes all novel and non-obvious combinations andsubcombinations of the various elements, features, functions and/orproperties disclosed herein. Similarly, where the claims recite “a” or“a first” element or the equivalent thereof, such claims should beunderstood to include incorporation of one or more such elements,neither requiring nor excluding two or more such elements.

1. A device for sorting particles, comprising: a channel structuredefining a channel having an inlet and first and second outlets; a firsttransport mechanism configured to create a particle stream of firstparticles and one or more second particles, each particle travelingalong the channel from the inlet toward the first outlet and disposed ina fluid supported by the channel structure; and a second transportmechanism configured to be pulse-activated to selectively move at leastone of the second particles from the particle stream and toward thesecond outlet, wherein the channel structure defines a passage disposedin fluid communication with the channel and generally opposing thesecond outlet, and wherein the passage includes a fluid diode configuredto restrict fluid backflow created by operation of the second transportmechanism.
 2. The device of claim 1, wherein the channel structureincludes a substrate and a plurality of thin-film electrical devicesformed on the substrate, and wherein the second transport mechanism isincluded in the thin-film electrical devices.
 3. The device of claim 2,wherein the channel structure includes a fluid barrier connected to thesubstrate so that the thin-film electrical devices are disposed betweenthe substrate and the fluid barrier.
 4. The device of claim 1, whereinthe first transport mechanism is configured to create a flow of thefluid through the channel, and wherein the flow of the fluid creates theparticle stream.
 5. The device of claim 4, wherein the first transportmechanism is configured to produce a pressure drop along the channel. 6.The device of claim 1, wherein the channel structure is configured sothat the particle stream follows a path from the inlet to the firstoutlet without operation of the second transport mechanism, and whereinthe second transport mechanism is configured to exert pressure pulsesdirected transverse to the path.
 7. The device of claim 6, wherein atleast one of the pressure pulses is configured to move a fraction of thefluid from the path, the fraction including the at least one secondparticle.
 8. The device of claim 1, wherein the second transportmechanism includes at least one of a heater element and a piezoelectricelement.
 9. The device of claim 1, wherein the channel is a firstchannel and the inlet is a first inlet, the channel structure defining asecond channel adjacent to the first channel and configured to carryanother fluid from a second inlet to a third outlet, and wherein thesecond outlet of the first channel places the first channel in fluidcommunication with the second channel.
 10. The device of claim 1,further comprising an optical sensor configured to sense the at leastone second particle in the particle stream, the optical sensor beingcoupled to the second transport mechanism so that sensing the at leastone second particle actuates the second transport mechanism.
 11. Adevice for sorting particles, comprising: a channel structure definingfirst and second channels that extend adjacent one another and betweenrespective pairs of opposing ends of the first and second channels, thechannel structure further defining a transverse channel that connectsthe first channel to the second channel intermediate the pair ofopposing ends of each channel; a first transport mechanism configured tosend respective first and second streams through the first and secondchannels, the first stream including first particles and one or moresecond particles; and a second transport mechanism configured toselectively move at least one of the second particles from the firststream in the first channel to the second stream in the second channelvia the transverse channel, wherein the channel structure defines apassage disposed in fluid communication with the first channel andgenerally opposing the transverse channel, and wherein the passageincludes a fluid diode configured to restrict fluid backflow created byoperation of the second transport mechanism.
 12. The device of claim 11,wherein the channel structure includes a substrate and a plurality ofthin-film electrical devices formed on the substrate.
 13. The device ofclaim 11, wherein the first particles and the one or more secondparticles are different types of cells.
 14. The device of claim 11,wherein the first stream follows a path, and wherein the secondtransport mechanism is configured to apply transient pressure pulses tothe first stream and transverse to the path.
 15. The device of claim 11,wherein the transverse channel provides the same path between the firstand second channels whether or not the second transport mechanism isselectively moving a second particle.